Background: The coincidence of recurrent respiratory symptoms and gastroesophageal reflux (GER) is a well-known phenomenon in infants. Twenty-four-hour pH metry is the presumed gold standard of diagnostic tools for this symptom complex, but with this method, only acid (pH <4) and alkaline (pH >7) GER can be detected. Gastroesophageal reflux with an esophageal pH in the physiological range (pH 5-6.8) may represent many cases of clinically relevant GER unrecognized by pH metry. In this study the intraluminal multiple electrical impedance (IMP) procedure for complete registration of GER was compared with pH metry for its diagnostic value in the presence of respiratory symptoms.
Methods: Twenty-two infants with recurrent regurgitation or pulmonary problems were investigated simultaneously with IMP, pH metry, and polygraphy during two feeding periods. Heart rate, oxygen saturation, sleep states, and oronasal flow were recorded, among other parameters.
Results: Three hundred sixty-four occurrences of GER were detected by IMP; only 11.4% had a pH less than 4 and were therefore recognized by pH metry. Three hundred twelve (84.8%) occurrences were associated with breathing abnormalities, and 11.9% of these were detected by pH metry. Nineteen instances were accompanied by a decrease of oxygen saturation of more than 10% of the initial value. Only three (15.8%) of these had a pH less than 4. The remaining 16 reflux episodes were recognized by IMP only. After software-aided preselection, 165 instances of apnea were visually validated, 49 of which were accompanied by GER. Thirty-eight (77.6%) of these were exclusively recorded by IMP.
Conclusions: The use of pH metry alone cannot detect most GER incidents accompanied by respiratory symptoms and therefore does not appear to be suitable for this approach. The pH-independent IMP technique promises to be a reliable tool for presumably GER-associated respiratory symptoms.